Endoscopy is a medical procedure used to examine the internal structure of the gastrointestinal system. It can be applied for both diagnostic and therapeutic purposes.

For Diagnostic Purposes: Endoscopy may be used to determine the cause of various symptoms and conditions, including:
* Abnormal bleeding (e.g., blood in stool, vomiting blood)
* Persistent abdominal pain
* Difficulty swallowing (dysphagia) or a sensation of esophageal obstruction
* Persistent nausea or vomiting
* Chronic diarrhea or constipation
* Unexplained weight loss
* Investigation of conditions such as stomach ulcers, inflammations (infections), pancreatitis, or gallstones
* Assessment of tumors or other digestive system disorders, their causes, and spread.

For Therapeutic Purposes: Equipped with special instruments, the endoscope can also be used for various therapeutic procedures. These procedures include:
* Dilation of esophageal strictures
* Drainage of accumulated fluids in the body
* Removal of polyps or small tumors (polypectomy)
* Extraction of foreign bodies
* Even the removal of certain small organs, such as an infected gallbladder in specific situations.

Other Applications: Endoscopy is sometimes combined with other imaging methods, such as ultrasound. In this technique, called Endoscopic Ultrasound (EUS), an ultrasound probe is attached to the endoscope. This allows for detailed images of the esophageal and stomach wall layers, while also enabling clearer and more detailed examination of hard-to-reach organs like the pancreas.